1. Field
The disclosure of the present patent application relates to ocular surgery, and particularly to an infusion cannula system for pars plana vitrectomy.
2. Description of the Related Art
Pars plana Vitrectomy (PPV), or simply vitrectomy, is a microsurgical procedure frequently performed by retina surgeons to surgically treat various retina conditions requiring the introduction of fine delicate microsurgical instruments within the eye. It is the second-most frequently performed procedure, after cataract surgery. In recent years, these delicate instruments have gone a long way towards better performance through continuous research and instrument development.
During vitrectomy, the vitreous gel is removed by an instrument called the vitreous cutter and is replaced by a balanced salt solution (BSS) to maintain the ocular pressure and structure. Typically three sclerotomies are performed, one inferiorly for an infusion cannula and two superiorly for a light and for insertion of instruments, such as a cutter, forceps, etc. The balanced salt solution is injected into the vitreous cavity by the infusion cannula system, which is controlled by the vitrectomy machine that maintains eye pressure within normal range throughout the surgery. It is very crucial that the infused solution is injected into the vitreous cavity, and in cases in which this fluid is not injected into the vitreous cavity, serious complications are likely to occur.
It is the responsibility of the surgeon to ensure that the inner part of the infusion cannula is placed well within the vitreous cavity (by visually looking at the tip of the inner side of the cannula) before initiating the flow of balanced solution. The existing infusion cannula system often has a standard length extending inside the eye, which is either 4 or 6 mm. The 4 mm length is the most commonly used and is sufficient for most cases. However, in some cases, as in undilated pupil, hazy media, and complex retinal detachments (as in trauma), it may be very difficult to ensure that the inner part of the cannula is within the vitreous cavity, and thus longer cannulas are required to ensure correct placement. On the other hand, some cases require shorter cannulas, as a 4 mm cannula might be too long and may cause damage to the natural lens of a small eye in a premature baby.
Therefore, the standard 4 mm cannula is not acceptable for all cases since some eyes need longer cannulas, while others require shorter infusion cannulas for safer surgery. Thus, an infusion cannula system for pars plana vitrectomy solving the aforementioned problems is desired.